Sailing ships require an additional propulsion system when wind conditions are insufficient to propel the sailing ship, or when maneuvers are carried out for docking and undocking. Sailing ship propulsion systems in which an internal combustion engine drives a propeller are known. The internal combustion engine is usually in the form of a diesel engine. In the motor mode, the sailing ship is steered using a rudder blade which is also used for steering in the sailing mode.
The catalog entitled “Integrated Starter Motor Generators” from the company Iskra Avtoelektrika, which is the owner of SI 22377 A, shows a ship propulsion system which comprises a parallel hybrid drive of the type described in SI 22377 A, and a stern drive. A Z-shaped, two-fold redirection of the drive train to the propeller takes place in the stern drive via two bevel gear systems. The first clutch is in the form of a multi-disk clutch or claw clutch. This parallel hybrid drive can be used to select the following operating modes: in a starter operating mode, the first clutch is engaged and the second clutch is disengaged. In this case, the electric machine functions as a starter and starts the internal combustion engine. As soon as the internal combustion engine is running, the drive system is automatically switched via the electronic control unit to the generator mode, in which the first clutch is likewise engaged and the second clutch is disengaged. The internal combustion engine drives the electric machine which functions as a generator and therefore charges the battery. Optionally, the battery can be charged via the electric power grid using the converter-charging unit while the ship is docked in the harbor. In the electric drive mode, the first clutch is disengaged and the internal combustion engine idles. The second clutch is engaged and therefore the electric machine, which now functions as a motor, drives the propeller. In a so-called booster mode, both clutches are engaged and the electric machine and the internal combustion engine operate in parallel. The cumulative drive power of the two machines drives the propeller.
In the stern drive shown, the direction of thrust of the propeller is reversed by reversing the propeller rotation, which may be necessary, for instance, to reverse the direction of travel when docking or undocking. To this end, a double-cone clutch which can be switched between the two directions of rotation is provided to change the rotational direction of the propeller. The solution with the double-cone clutch includes additional components and is difficult to assemble, which are disadvantages. Moreover, the shifting procedure is accompanied by poor shifting behavior in the form of torque surges and the associated material stress, as well as jerky propulsion and an audible noise. A further disadvantage associated with reversing the direction of thrust by reversing the rotational direction of the propeller is the reduced efficiency in the conversion of mechanical energy into energy of flow since the propeller blade geometry is typically designed or optimized for only one rotational direction.